Frames with multiple blades are commonly used for cutting or sawing blocks of a masonry material such as concrete, marble, granite, sandstone, limestone, fired brick or a like material, as well as for cutting blocks of composite material made of stone or marble chippings bound together by a binder material. Such frames may have steel blades or steel blades equipped with diamond-containing segments, with each of the blades being maintained under tension. Such tension may be supplied, for example, by one or more tension rods.
For example in U.S. Pat. No. 4,566,427, a device for cutting blocks of granite, marble, stone and similar materials is provided. Such a device includes a plurality of sawing blades; a blade-carrying frame into which at least two sawing blades are fixed and having slide means for directing horizontal motion of said frame; a drive motor unit connected to said blade-carrying frame for displacing said sawing blade in a reciprocating motion, a slide-carrying frame of generally rectangular cross-section, upright supports, a guide unit on each upright support connected to said slide-carrying frame for directing vertical movement of said slide-carrying frame, said slide means of said blade-carrying frame being adapted to fit within said slide-carrying frame, and vibration damping means for creating pressure on the top, bottom, and each side of said slide means to urge said slide means away from contact with said slide-carrying frame, thus providing a vibration dampened connection between said slide-carrying frame and said blade-carrying frame, whereby vibrations to the sawing blades is minimized.
In another example, in U.S. Pat. No. 5,233,968, a sawing machine including multiple blades in a stiff support framework is described to saw stone blocks, and particularly granite. The sawing machine uses rectilinear travel wherein, in correspondence of the abrasion zone and in addition to the conventional translatory motion, a blade frame is used with a hammering or percussion movement of the saw blades onto the stone block being cut. The machine is designed so that the blades may “jump”, meaning that the blades may be lifted from the bottom of the cutting channels and then be dropped again therein in a short, rapid movement.
In another granite sawing operation employing horizontal frame saws, each frame saw has up to 250 steel blades each more than 3 meters long, 3-5 mm thick, and 50-200 mm tall. After sawing granite or marble blocks into slabs, the slabs are polished to ultimately generate finished components such as tiles and blocks. Slabs may be considered to be sufficiently flat if the surface deviates less than about 1.5 mm from a plane. Slabs of thickness variation of greater than about 2 mm cannot be sorted and polished, and often must be scrapped. In another example, a slab's thickness variation may be considered acceptable for polishing if the difference between the thickest and thinnest points in the slabs is less than about 10% of the slab's nominal thickness.
To meet finished granite/marble product quality control requirements such as those detailed above, the blades must not deviate from a substantially straight path as they cut through a block of marble or granite. Blade deviation can arise when local forces cause the blade to twist, flex, or bend out of a plane, leading to cuts deviating from a straight path and slabs exceeding the allowable thickness variation. Additionally, blade deflection causes premature blade wear due to blade flexing, buckling, and fracture.
One source of local forces causing blade flexing or deviation is the irregularities of the masonry material to be cut or sawed. Mined masonry materials typically have internal faults. Granite and marble materials, endowed with color and vein structure, are usually defective due to fracturing during geological formation. Some of the defects may be external, as caused by mining conditions with drill holes and other asperities. As saw blades are used to cut as-mined masonry materials, the blades can experience highly variable forces due to the irregularities in the materials which may cause premature wear in steel blades and deviation from a substantially parallel cut in the slab. As an additional problem in cutting or sawing masonry materials, superabrasive particles of the saw blades may be detached or pulled-out from superabrasive containing blades during operation. This pull-out of the superabrasive particles in the blades is heightened by the irregularities of the masonry material.
Because of the intrinsic defects in the raw masonry materials and the prior art cutting and sawing systems, the cutting of slabs from marble and other rock is costly due to the large amount of reject material and/or machine wear. There is a need for improved methods and systems for cutting slabs of masonry materials such as granite, marble, rock, and the like.